Emanuel Steward, who trained boxing champions Thomas Hearns, Lennox Lewis, Oscar De La Hoya and Wladimir Klitschko and analyzed fights as an HBO Sports ringside commentator since 2001, has died. He was 68.

Steward, owner of the fabled Kronk Gym in Detroit and an International Boxing Hall of Fame trainer, died Thursday at a Chicago hospital.

ESPN reported Friday that Steward had been hospitalized since September, causing him to miss two HBO broadcasts, and underwent surgery. His sister, Diane Steward Jones, said the surgery was for the stomach disorder diverticulitis, though many others who knew the trainer said it was for advanced cancer.

“Manny was a respected colleague who taught us so much not only about the sweet science but also about friendship and loyalty,” HBO Sports president Ken Hershman said. “His energy, enthusiasm and bright smile were a constant presence. Ten bells do not seem enough to mourn his passing.”

HBO Sports commentator Jim Lampley, who worked alongside Steward for more than a decade, said Steward’s wisdom and common touch made him special.